1. Field of the Invention
The present invention relates to a lens barrel having an image blur correction mechanism, and an image pickup apparatus such as a film camera, a digital camera, or a digital video camera, which is equipped with the lens barrel.
2. Description of the Related Art
Some lens barrels mounted on an image pickup apparatus such as a digital camera are equipped with an image blur correction mechanism that corrects for a blur of a subject image formed on a light-incident surface by shifting a part of taking lenses so as to prevent image degradation caused by camera shake or the like.
There has been proposed a lens barrel which has, as mechanisms that linearly guide taking lenses in a direction of an optical axis while inhibiting rotation of the lenses, two straight advance mechanisms consisting of one comprised of a first straight advance groove and a first straight advance key and one comprised of a second straight advance groove and a second straight advance key (Japanese Laid-Open Patent Publication (Kokai) No. 2012-63755). According to this proposal, the two straight advance mechanisms have an area where a straight advance key and a straight advance groove engage and an area where they do not engage. In an area where a cam groove of a cam cylinder and one straight advance groove cross each other, a straight advance key is engaged with the other straight advance groove.
Also, there has been proposed a lens barrel which has a plurality of partial straight advance guide members which, when linearly guiding a straight moving member holding an optical element in a direction of an optical axis through rotation of a rotary ring, linearly guides the straight moving member in the direction of the optical axis in a plurality of different split moving ranges (Japanese Laid-Open Patent Publication (Kokai) No. 2011-8046).
According to both Japanese Laid-Open Patent Publication (Kokai) No. 2012-63755 and Japanese Laid-Open Patent Publication (Kokai) No. 2011-8046, a plurality of straight advance mechanisms are engaged or disengaged depending on areas. For this reason, when only part of the plurality of straight advance mechanisms is engaged, an oscillation phenomenon of the lens barrel may occur because vibrations occurring when a lens of the image blur correction mechanism shifts are amplified, and particularly when the lens is heavy, the oscillation phenomenon is likely to occur.